Construction of current-carrying resistors



W. L. BROOKS.

CONSTRUCTION OF CURRENI CARRYING RESISTORS.

APPLICATION FILED FOVJQ, I920.

Patented Apr. 18, 1922.

Invent ow 3 1 ace L $r-o 0R5 m @2 7 m *hsiflttowngy UNITED STATES PATENT] OFFICE.

WALLACE L. BROOKS, OF SOHENEOTADY, NEW YORK, ASSIGNOR TO GENERAL ELEC- TRIO COMPANY, A CORPORATION OF NEW YORK.

CONSTRUCTION OF CURRENT-CARRYING RESISTORS.

Specification of Letters Patent. Patented Apr. 18, 1922.

Application filed November 2, 1920. Serial No. 421,367.

It is quite customary to use as a i'esist-.

ance element the alloy manganin, especially for accurate measurements where it is essential that errors due to varying temperature be minimized. T'oprovide terminals for these stripsof manganin, copper terminal bars are utilized which also serve to carry the appropriate binding screws to connect the manganin strips to an outside circuit. It has been found that difficulties occur when it is attempted to solder the manganin strips directly to heavy copper terminal bars. This difiiculty arises from the fact that it is necessary to use silver sold r to make a good connection which will not be affected by conditions of service. A high temperature must be used to perform this soldering operation. Since the terminal bars have a relatively large mass, it is difficult to keep them heated at the required temperature without. heating thealloy to a point which destroys its electrical and mechanical characteristics. Especially isthis true where a plurality of strips are joined to a common terminal bar. It is thus the main object of my invention tofacilitate the securing of the manganin strips to the terminal bars.

For a better understanding of my invention, attention is called to the accompanying drawing in which Fig. 1 is a view in perspective, showing the entire current-carrying resistor constructed according to'my invention; and Fig. 2 is a detail view showing on an enlarged scale how the manganin strips are held to the terminal bars.

Referring now more in detail to the drawings, in which like reference characters refer to like parts throughout, the resistance element '11 is formed of a thin stri of manganin bent back and forth upon itself in the manner clearly shown and ap'propri-.

ately held on an insulating base 12 by means of the insulating blocks 13. The ends of the strip 11 are secured in the holders or terminal bars 14 which carry the binding screws 15 for appropriate connection of the resistor into the circuit. of the metals made use of is such that to solder them together with ordinary solder they would have a variable resistance value in service; to remedy this, silver solder and a relatively high temperature must be used. I Since the mass of the copper terminal bars 1 1 is quite large, a difliculty presents itself in doing this without overheating and disturbing the electrical characteristics of the manganin. To overcome this difficulty I make use of a member 16 of relatively small mass which is ordinarily made of copper and which embraces the strip 11 as shown in Fig. 2. This copper element 16 is first soldered with silver solder to the manganin strip 11 and since its mass is small, no difficulty is experienced in effecting a proper union, and in retaining the alloy in its proper condition. After'this is accomplished, the member 16 is appropriately soldered with ordinary solder within theterminal bar 14 in which a slot may be milled within which the member 16 may be inserted. The layers of solder connecting the elements are indicated at 17.

\Vhile I have shown one/embodiment of The character my invention, I do not wish to be limited thereto but aim to embrace in the appended claims all modifications falling fairly within the scope of my invention.

Vhat I claim as new and desire to secure by Letters Patent of the United States, is:

1,. In a current-carrying resistor, in combination, a manganin strip, copper terminal bars for said strip, copper members each embracing said strip and soldered to the strip and to the terminal bars.

2. In a current-carrying resistor, in combination, a pair of copper terminal bars, each of said bars having a slot, a manganin resistance strip, and a pair of U-shape'd copper elements each embracing an end of said strip and soldered thereto, said elements being also soldered within the slots in the terminal bars.

In witnesswhereof, I have hereunto set my hand this first day of November, 1920. 

